dediprog: add support for chip select.

Thanks to the traces captured and tests done by Martin Roth, and confirmed
by tests and analysis by Joshua Zarr too, we can now use both target chips
on the Dediprog SF100.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

git-svn-id: svn://coreboot.org/flashrom/trunk@1673 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1